Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

The invention relates to a cannula for medical use, which is obstructed
at the distal end thereof and which has an occlusion balloon enabling
regionalization of the extracorporeal circulation, it being possible for
said cannula to be multiperforated.

Claims:

1. A cannula for medical use, comprising a proximal end (1) and a distal
end (2) that are connected by a body (3) comprising a first hollow tube
(11) of which the proximal end (12) is open and the distal end (13) is
closed, and a second hollow tube (21) of which the proximal end (22) and
the distal end (23) are open, the distal end (23) of said tube (21)
leading to the inside of an occlusion element (4) located in proximity to
the distal end (2) of the cannula, said first hollow tube (11) having at
least one orifice (14) arranged near the distal end (2) of the cannula
and located proximally with respect to the occlusion element (4), adapted
for use in carrying out a regional extracorporeal circulation for organ
donation after cardiac death (DCD).

2. A cannula for medical use, comprising a proximal end (1) and a distal
end (2) that are connected by a body (3) comprising only a first hollow
tube (11) of which the proximal end (12) is open and the distal end (13)
is closed, and a second hollow tube (21) of which the proximal end (22)
and the distal end (23) are open, the distal end (23) of said tube (21)
leading to the inside of an occlusion element (4) located in proximity to
the distal end (2) of the cannula, said first hollow tube (11) having a
plurality of orifices (14) arranged along its length near the distal end
(2) of the cannula and all located proximally with respect to the
occlusion element (4).

3. The cannula as claimed in claim 1, characterized in that said first
tube (11) has a plurality of orifices (14) along its length.

4. The cannula as claimed in claim 1, characterized in that the two tubes
(11) and (21) are concentric.

5. The cannula as claimed in claim 1, characterized in that said second
tube (21) is situated on the periphery of said first tube (11).

6. The cannula as claimed in claim 1, characterized in that the distal
end (2) of the cannula has a hemispherical shape or the shape of a cone.

7. The cannula as claimed in claim 1, characterized in that the diameter
of the first tube (11) is 4 to 5 times greater than the diameter of the
second tube (21).

8. The cannula as claimed in claim 1, characterized in that said orifices
(14) are located at a distance of between 6 and 40 cm from the distal end
(2).

9. The cannula as claimed in claim 1, characterized in that it has a
length greater than or equal to 50 cm.

10. The cannula as claimed in claim 1, characterized in that the internal
diameter of the body (3) is between 3.96 and 6.6 mm.

11. The cannula as claimed in claim 1, characterized in that it is made
of flexible plastic.

12. The cannula as claimed in claim 2, characterized in that the two
tubes (11) and (21) are concentric.

13. The cannula as claimed in claim 2, characterized in that said second
tube (21) is situated on the periphery of said first tube (11).

14. The cannula as claimed in claim 2, characterized in that the distal
end (2) of the cannula has a hemispherical shape or the shape of a cone.

15. The cannula as claimed in claim 2, characterized in that the diameter
of the first tube (11) is 4 to 5 times greater than the diameter of the
second tube (21).

16. The cannula as claimed in claim 2, characterized in that said
orifices (14) are located at a distance of between 6 and 40 cm from the
distal end (2).

17. The cannula as claimed in claim 2, characterized in that it has a
length greater than or equal to 50 cm.

18. The cannula as claimed in claim 2, characterized in that the internal
diameter of the body (3) is between 3.96 and 6.6 mm.

19. The cannula as claimed in claim 2, characterized in that it is made
of flexible plastic.

Description:

[0001] The invention relates to a novel arterial cannula which can be used
to carry out a regional extracorporeal circulation, and which in
particular is used for organ donation after cardiac death (DCD).

[0002] Organ donation after cardiac death (DCD) has been legal again in
France since 2005.

[0003] The Biomedicines Agency has published the procedure to be followed
when removing the kidneys and liver from donors of this type. This
procedure involves the placement of arterial and venous femoral cannulas,
in order to re-establish the normothermic circulation, and the placement
of a Fogarty catheter by a contralateral femoral arterial route, which
catheter is deployed and its balloon positioned approximately 5 cm above
the diaphragm in order to regionalize the extracorporeal circulation and
thereby avoid cardiac and cerebral reperfusion.

[0004] The procedure stipulates that circulatory assistance be set up
after the positioning of the Fogarty catheter. This circulatory
assistance must be operational 150 minutes after the cardiac arrest of
the patient.

[0005] If this deadline, which is very short and sometimes impossible to
achieve in practice, cannot be met, the procedure has to be stopped and
the organs cannot be removed.

[0006] The average time of arrival of potential donors after cardiac death
is 113±31 minutes (D. Barouk et al. Reanimation 2010 (19) 1S: SP 105).
The procedure for introducing the Fogarty catheter takes approximately 20
to 30 minutes alone. It is then necessary to introduce the two cannulas
in order to establish the regionalized circulation, which takes about
another 20 to 30 minutes in the absence of technical difficulties. Thus,
from the start of the intervention, a minimum period of 40 minutes is
needed before being able to begin removing the organs. At this stage of
the procedure, an average period of 153 minutes has therefore elapsed
since the cardiac arrest, provided there have been no technical
difficulties when inserting the cannulas.

[0007] It will therefore be appreciated that the speed of intervention and
the speed of introducing the elements needed for circulatory assistance
are crucial in organ donation after cardiac death (DDC).

[0008] The invention thus relates to an arterial cannula which is closed
at its distal end and which is provided with an occlusive balloon
permitting the regionalization of the extracorporeal circulation. In a
preferred embodiment, this cannula is multi-perforated, which permits
perfusion of the organs that are to be removed (kidneys and liver).

[0009] The use of this cannula thus makes it possible, in a single step,
to install the element permitting the regionalization of the normothermic
circulation and also the source for supply of oxygenated blood. It is
thus possible to speed up the placement of the pre-requisites before the
organs are removed, and therefore to improve the physiological state of
the transplants by reducing the hot ischemia time, while at the same time
reducing the failure rate currently observed as a result of the
impossibility of observing the deadlines imposed on the establishment of
the normothermic circulation. Finally, the use of this cannula makes it
possible to avoid the incision in the contralateral femoral artery of the
potential donor, thus enhancing the integrity of the body.

[0010] Cannulas that are coupled to occlusive elements already exist.

[0011] The document WO 99/37202 describes a cannula for maintaining blood
flow in a patient whose heart has stopped, an occlusion element, allowing
the ascending aorta to be obstructed in order to maintain the
regionalization of the circulation. This cannula is open at its distal
end and also has lateral ports located in proximity to the distal end of
the cannula, in order to permit the circulation of the blood if the end
is obstructed by the occlusion element.

[0012] The document WO 99/30766 describes a cannula coupled to an
occlusive element located at the distal end thereof. This cannula can
comprise three tubes (or lumens) for a) injecting a cardioplegia
solution, b) injecting a fluid to inflate the occlusive element, and c)
being used for aspiration. The solution supplied can be delivered
upstream or downstream of the occlusive element.

[0013] US 2004/102734 describes two embodiments of cannulas having a
balloon at their distal end, and also orifices located proximally with
respect to said balloon. These devices are envisioned for use in cardiac
surgery. These cannulas are thus intended to be used via the aorta. The
cannula of the first embodiment (described in FIG. 1 of D1) has three
lumens. The cannula of the second embodiment (illustrated in FIGS. 6 and
7 of D1) has two lumens. However, the two lumens have open proximal and
distal ends (FIG. 7, and paragraph

[0071]).

[0014] U.S. Pat. No. 6,267,747 describes cannulas having a balloon at
their distal ends, and also orifices located proximally with respect to
said balloon. These cannulas are intended for cardiac surgery (paragraph
"Field of the invention"). They must permit the introduction of a
cardioplegic liquid downstream of the occlusion element (column 2, lines
25-44). The cannulas of D2 have at least three lumens (FIG. 2).

[0015] US 2005/171505 describes cannulas with three channels. These
cannulas are not closed downstream of the occlusion element, as they have
orifices (3) downstream of this element (abstract, and FIG. 8).

[0016] US 2003/229332 describes a cannula which is more particularly
intended for withdrawal of an element (such as a kidney stone).

[0017] U.S. Pat. No. 4,892,519 describes a cannula having orifices
downstream of the balloon.

[0018] None of these documents describes the use of a cannula in carrying
out a regional extracorporeal circulation for organ donation after
cardiac death (DCD).

DESCRIPTION OF THE FIGURES

[0019] FIG. 1 shows a side view of a cannula according to the invention.
This cannula has a proximal end (1) and a distal end (2) that are
connected by a body (3) comprising a first hollow tube (11) of which the
proximal end (12) is open and the distal end (13) is closed, and a second
hollow tube (21) of which the proximal end (22) and the distal end (23)
are open, the distal end (23) of said tube (21) leading to the inside of
a toric occlusion element (4) located in proximity to the distal end (2)
of the cannula, said first hollow tube (11) having three orifices (14).
In this specific case, the distal end (2) of the cannula has the shape of
a rounded cone.

[0020] FIG. 2 shows plan views of the cannula according to the invention.
In FIG. 2A, the two lumens (11) and (21) are concentric. In FIG. 2B, the
lumen (21) is located on the edge of the body (3).

[0021]FIG. 3 shows a cannula according to the invention introduced into
the aorta of a donor via the right femoral artery. The renal arteries
(31, 32) and the celiac trunk (33) are indicated. Four orifices (14)
located near the proximal end (2) are shown.

[0022]FIG. 4 shows a side view of another cannula according to the
invention. It depicts the proximal end (1) and the distal end (2) that
are connected by the body (3) comprising a first hollow tube (11) of
which the proximal end (12) is open and the distal end (13) is closed,
and a second hollow tube (21) of which the proximal end (22) and the
distal end (23) are open, the distal end (23) of said tube (21) leading
to the inside of an occlusion element (4) of cylindrical shape located in
proximity to the distal end (2) of the cannula, said first hollow tube
(11) having two orifices (14).

[0023] The invention thus relates to a cannula for medical use, comprising
a proximal end (1) and a distal end (2) that are connected by a body (3)
comprising a first hollow tube (11) of which the proximal end (12) is
open and the distal end (13) is closed, and a second hollow tube (21) of
which the proximal end (22) and the distal end (23) are open, the distal
end (23) of said tube (21) leading to the inside of an occlusion element
(4) located in proximity to the distal end (2) of the cannula, said first
hollow tuber (11) having at least one orifice (14) arranged near the
distal end (2) of the cannula and located proximally with respect to the
occlusion element (4).

[0024] The orifice (14) thus connects the lumen (11) to the outside of the
cannula.

[0025] Within the context of the present invention, the term "lumen" can
be used in place of the term "tube".

[0026] The terms "near the distal end" and "in proximity to the distal
end" refer to a distance of between 1 and 10 cm from the distal end (2).

[0027] This use of the cannula (carrying out a regional extracorporeal
circulation for organ donation after cardiac death (DCD)) therefore
requires the presence of only two lumens: one lumen for inflating the
inclusion element, and one lumen for re-establishing regionalized blood
flow. It is thus clear that the cannula comprises only a lumen (11) and a
lumen (21).

[0028] In a preferred embodiment, the distal end (2) of the cannula is of
hemispherical shape. More preferably, this distal end (2) has the shape
of a cone with a rounded point.

[0029] This shape of the distal end (2), and the fact that it narrows and
has an internal diameter smaller than the diameter of the body (3) of the
cannula, makes it possible to reduce the risk of damaging the arteries
during the introduction of the cannula.

[0030] The occlusion element (4) can in particular be fixed to the cannula
by a collar situated at the end of the cannula. This occlusion element is
preferably a balloon and can be designated as such in the present
description. When it is contracted, it lies against the outer surface of
the body (3) of the cannula.

[0031] In a preferred embodiment, the occlusion element (4) is inflated by
introduction of a fluid into this element via the second lumen (21) of
the cannula. In this embodiment, a liquid solution is preferably used
(such as physiological saline).

[0032] In other embodiments, the balloon (4) is filled with foam and is
contracted, for insertion into the body of the patient, by application of
a negative pressure or because it is covered by a sleeve. The balloon
dilates, in order to obstruct the aorta, when the sleeve is withdrawn or
when application of the negative pressure stops.

[0033] This occlusion element can be spherical, conical, elliptic, toric
or funnel-shaped. The inner surface of the occlusion element (4) is
adjacent to the outer surface of the body (3) of the cannula, the outer
surface serving to occlude the aorta of the patient.

[0034] Some documents, for example U.S. Pat. No. 6,231,544, describe
producing a cannula comprising a balloon.

[0035] In a preferred embodiment, this occlusion element (4) is placed
approximately 2-3 cm before the distal end (2) of the cannula.

[0036] In a preferred embodiment, the occlusion element is said to be
"compliant", that is so say it adapts to the diameter of the artery once
inflated (even when inflated to the maximum extent), without any risk of
damaging the wall of the artery. Its maximum diameter after inflation is
less than 45 mm. A compliant balloon is able to deform in order to adapt
to the diameter of the aorta, even when inflated to the maximum extent.

[0037] It will be noted that the diameter of the aorta of patients is of
the order of 24 mm for women and 24 to 27 mm for men.

[0038] The cannula according to the invention is intended in particular to
be introduced via the femoral artery of a patient and inserted via the
aorta until the occlusion element is located at the aortic orifice of the
diaphragm.

[0039] The proximal end of each of the lumens is thus advantageously
provided with a tubular connecting base for connecting the first lumen to
a pump for injection of oxygenated blood and for connecting the second
lumen to a pump or a syringe for inflating or deflating the occlusion
element.

[0040] The first lumen (11) is thus intended to permit circulation of the
oxygenated blood introduced from the proximal end. It is expedient that
it can be released in the arteries of the patient in order to be able to
continue irrigating the organs in question (liver and kidneys). It is
thus expedient for the orifice or orifices (14) to permit a flowrate of
the order of 4 liters per minute.

[0041] In a particular embodiment, the cannula has a plurality of orifices
(14) distributed along the length of the first lumen (11). These orifices
are preferably distributed all around the body (3) and are located at a
distance of between 6 to 10 cm and 30 to 40 cm from the distal end (2) of
the cannula.

[0042] As has been mentioned above, cardiac and cerebral reperfusion
should be avoided. It is therefore clear that the orifices (14) intended
to release the oxygenated blood introduced from the proximal end of the
lumen (11) are all located proximally with respect to the occlusion
element (4). It is also clear that there can be no orifice (14)
(connecting the lumen (11) to the outside of the cannula) located
distally with respect to the occlusion element (4), which would lead to
reperfusion of the higher organs (heart or brain).

[0043] In a preferred embodiment, the internal diameter of the cannula is
between 12 and 20 French (Fr). The French is the unit of measurement of
the diameter of catheters and corresponds to 0.33 mm. In a preferred
embodiment, the diameter of the cannula is between 15 and 18 Fr.

[0044] In order to maintain the blood flowrate at the outlet of the
cannula via the orifice or orifices (14), it is preferable that the
surface area of these orifices is equal to the surface area of the
cannula. Thus, the surface area of the cannula is of the order of 20
mm2 when the diameter of the cannula is 15 Fr. The total surface
area of the orifices (14) must therefore be of this order. Thus, it is
conceivable to provide 3 orifices (14) of the order of 3 mm in diameter,
or 4 orifices (14) of the order of 2.5 mm in diameter, or 8 orifices (14)
of approximately 1.8 mm in diameter. Another number of orifices (14) may
be envisioned, their diameter then being easily calculated in order to
meet the requirements in respect of the blood flowrate that has to be
maintained in the arteries of the donor.

[0045] In a particular embodiment, the two tubes (11) and (21) are
concentric. In this embodiment, the central tube (21) is used for
circulation of the fluid intended to inflate the balloon, while the
radial tube (11) is intended for the flow of blood (FIG. 2A).

[0046] In the preferred embodiment, the second tube (21) is situated on
the periphery of the first tube (11), that is to say on an edge of the
first tube, or directly inside the material constituting the body of the
cannula (FIG. 2B).

[0047] In a preferred embodiment, the diameter of the first lumen (11) is
4 to 5 times greater than the diameter of the second lumen (21).

[0048] The cannula according to the invention must be inserted via the
femoral artery of the patient as far as the level of the diaphragm.
Provision is therefore made that it has a length greater than or equal to
50 cm, preferably about 80 cm.

[0049] The cannula according to the invention can be made of any material
suitable for medical use. It is preferably made of non-thrombogenic and
flexible plastic, so as to be able to pass easily through the arteries of
the patient. It can thus be made of silicone, polyurethane or
polytetrafluoroethylene (known under the trademark Teflon®).

[0050] The materials used to produce the occlusion element (4) are known
in the art. This occlusion element can thus be made of polyurethane.

[0051] The cannula according to the invention can be sterilized by any
means known in the art (for example using ethylene oxide or by beta or
gamma irradiation) and packed in packages that are opened at the time of
the operation.

[0052] As has been mentioned above, this cannula is used for carrying out
a regional extracorporeal circulation and is preferably used in a
procedure associated with removal of an abdominal organ such as the liver
or the kidneys, particularly in organ donation after cardiac death.

[0053] One of the advantages of the cannula according to the invention is
the possibility of perfusion of the oxygenated blood higher in the
patient's body, and therefore closer to the arteries leading to the
organs of interest (the celiac trunk leading to the liver, and the renal
arteries). Indeed, with the system of the prior art, the arterial cannula
releases the blood in the area of the branch between the iliac artery and
the aorta. It therefore has to "climb" the aorta in order to enter the
aforementioned arteries. The location of the orifices (14) directly under
the occlusion device means that the blood is released nearer these
arteries. This can therefore be an advantage for the quality of the
organs.

[0054] The invention also relates to a method for removing an abdominal
organ (liver, kidney) from a donor after cardiac death, said method
comprising the steps of:

[0055] a. inserting the cannula according to the
invention into a femoral artery, passing it into the aorta and
positioning it in such a way that the occlusion element is located at the
aortic orifice of the diaphragm,

[0056] b. introducing a venous cannula
into a femoral vein of the patient,

[0057] c. deploying said occlusion
element so as to block the circulation downstream of this element,

[0058]
d. establishing a normothermic extracorporeal circulation by way of the
cannula according to the invention and the venous cannula.

[0059] It is preferable to introduce the cannula into a femoral artery,
this artery being easily accessible within the limited time available to
the operator, but it can also be introduced into another artery, for
example an external iliac artery. This also applies to the venous cannula
mentioned in step c).